Method of treating leather



Sept. 13, P A BLA-fz METHOD 0F TREATING LEATHER t I I lllllllllnn. HNIIIIIHIIIIIU'VIIHIINHH l Il Filed Harsh 29. 1950 INVENTQR:

vPatented Sept.r 13, 1932 UNITED sTArEs'v rerun A. BLA'rz, or WEs'rovER HIL'IszDELAWARE 7. METHOD or TREA'rrNe LEATHER Appiica'fon flied Marchas, 1930.A serial m4351381.

My invention comprises a method of treating mineral (chrome) tanned leather; theessential- 'object of my invention being to preserve ormaintain the skins constituting .5 Suchleather in a-wet condition until ready for the step of dyeing or coloring.

A further object of my invention is to hold said mineral (chrome) tanned leather in a wet condition by maintaining itin a storie age bath of cold water. v

And a still further object of my invention is to maintain such tanned leather skins ina bathl of Vcold water kept at a relatively constant low temperature, above freezing, but not'exceeding, substantially, 45 F.r and in all instancesbelow a temperature favorable to bacterial growth.v 'f f 'Y i VThese and other features"ofmy'invention are more fully set'forth hereinafter; -refer- =-z ence being lhad to the accompanyingdrawing which illustrates, diagrammatically, a form ofV apparatus'whichmay be employed in carrying out my invention. 'l

In the manufacture of various types Aof A 1:5" 'leather by mineral (chrome) tannage, particularly leather made from kid and Vgoat Skins,`V cabrett-a, and allied animal pelts, and more or less generallyfknown as glazed kid, the final step before the skinscomprising .$11 'such leather are dried and made ready for the finishing steps, such as staking, glazing and/or ironing, or the like, is the step of coloring. The coloring of mineral (chrome) tanned leatheris eiected-by drumming such 1.11113 leatherv in the coloring solution. The skins are taken from the final tanning bath and while rstill completely wet therefrom" and after sorting and/or grading are placedin such coloring bath andv drummed therein until the skins have taken up the Vdesired shade; the time involved depending in some measure upon the weight of the skins and the color they are intended to have.

\ The step of coloring must be`.carried out while the leather is still wet from the tanning treatment in orderfthat Vthe coloring matter or dye may penetrate and permeate completely the surface, body, and fibres of the leather. Such coloring operation usually takes place at a'temperature-ofapprokimately 125 F. in order thatfthe fibres of the skins-#now completely tanned leather--mayb'e kept in'ka Ahighly swollen or openv statelfacilitating the penetration of the'dyeor other coloring mat# ter; thetemperatureof such'operationbein'g u somewhat higher thanv thatlat 'which' the steps of the V tanning operation aref'carriedout, which is usually at'orabout 60 F. f

The demand lis for colored leather; the range of colors being very extensive, with 00 shades or tones of many colors varying in greater or less degree.v In order to be in a position to supply the demand yfor"colored leather manufacturers, following theusual practice, carry forward the complete opera'- .i tions of tanningand coloring asi immediately successive steps in the preparation of'such leather, followed by theu'sual finishing steps which include staking, glazing and/or ironing, etc., until the completely finished product 7o vis the colored glazed 'kid or other leathercf commerce, ready for the manufacture of footcolored leather is employed.

.wear or for other purposes for which'such tion it is impossible to changesuch color, with the single exception rof 'making such skin black. But'this must Vbe doneat, additional expense, with a very definite `loss in value over the normallvalue of thecolored skin when Vthelatter is salableiy as` colored leather. (Many manufacturersl carry vast quantities of colored skins `in theirpinventories from year to year at a definite loss `be- .195

cause of the inability to properly gauge the demand for leather of particular colors, shades, or tones. AAnd until the demand for the particular color, shade/.or toney of the finished leather returns, lthis-leather can only 100 Unfortunately, the demand for'onefcolor 75 ror anotheris never uniform,`and manufacbe disposed of by changing the color to black, and at the additional expense.

When a mineral (chrome) tanned skin becomes dry, it is impossible to color it, as it is impossible to re-wet such skin. The very nature of mineral (chrome) tannage precludes such re-wetting and unless a skin is completely wet so that all pores are open and the fibres are in a more or less loose and soft condition it is impossible to color it. Chrome tanned leather is moisture repellant, and it can readily be understood therefore that when a skin is finished in one color no change in such color can be effected. At the best, the new color would have to be darker. Even the .blackening of colored skins is most Vunsatisfactory, and such blackening is only in the nature of a surface coating rather than a permeation of the black dye or coloring matter. And under the most favorable conditions in changing a colored skin to black, the grain surface undergoes an objectionable roughening that can not be eradicated.

If leather manufacturers could preserve the fully tanned skins in what might be termed an intermediate condition, ready for the coloring step, the difficulty of having to makeup large batches of colored skins in the hope that the particular shade-or color thereof would not greatly exceed the demand and the loss entailed by the carrying of large quantities ofrcolored skins in .storage until the particular color again came into favor might be overcome. Additionally, by keeping the' tanned skins in such intermediate condition, ,great expedition in the final finishing can be accomplished and orders can be filled with .certainty in a Vdefinite and much shorter space of time over the condition of filling an order from the raw state to the finished leather condition, where, necessarily, the whole operation must extend over .a period of weeks rather than days.

I' have discovered that if the skins tanned by mineral (chrome) tannage are maintained in a thoroughly wet condition by complete submergence in a bath of cold water, they may be kept for an indefinite length of time without deterioration; the mineral (chrome) tannag-.e bei-ng of .such a nature that the fibres ofl the skin are definitely set for lall time, and the keeping of the tanned skins in the wet condition will not cause any bleeding of Ythe tanning agents nor impair in any way the leather so tanned., or all'ect the hide substance that has been transformed into leather lby such mineral (chrome) tannage.

My invention consists in providing a bath Aof cold water in which the `mineral (chrome) tanned skins :are kept until wanted for the coloring operation. This water bath is preferably maintained 'in a `properly insulated tank or chamber, with means whereby such water may 'be kept zat Ya relatively con- :stal-1t low temperature.

By preference, a series of tanks or chambers will be provided, and means will be provided for cooling the same by the constant circulation of a cooling medium through suitably arranged pipes or coils. Any means of effecting circulation may be employed; the mechanical refrigerating means p in widespread use at the present time being a very satisfactory method of effecting the cooling of such water bath. lf desired, the water constituting the bath may be circulated, and it is within the scope and purview of my invention to employ ice as a means of cooling the water of such storage bath by placing the same directly therein as conditions may require. y

A constant temperature approximately not less than 35o F. and not greater than 45 F. is 'to be preferred, and in all instances such temperature must be so low as to preclude the possibility of bacterial growth. The skins may be kept indefinitely in such cold water bath. They are preferably placed therein in batches of so many dozen, and they may be loosely piled or arranged in any manner that will insure complete submergence .and a thoroughly wet condition. By preference,

the cold water storage bath is provided in an insulated chamber in order that the cir culation of the cooling medium may be constant, if necessary, though when the desired low temperature has been reached, such .circulation may cease. Suitable thermostatic means `controlling' the circulation of the cooling medium may be employed. It will be understood that each batch of skins placed in such bath is removed as a whole when they are to be colored, that is to say, there will be no piles containing skins placed in such bath at different times. ln practice, the storage tanks will be numbered and dated so that when `it i-s desired to remove a batch `of skins for coloring, the oldest batch will be removed first, and so on.

ln the accompanying and diagrammatic drawing, l may represent an insulated tank, having a cover 2 which is kept closed during the storage period. A Vsuitable refrigerating unit is indicated at 3, and this is in com munication with pipes .or coils 4l within the tank. These pipes or coils may be placed in any suitable manner that will insure proper circulation of a cooling medium to effect the desired cooling of the water bath. rllhey may be placed along th-e walls., or arranged to proj ect upwardly within the body of water.. lWith the knowledge that cooling proceeds downwardly, the coils or pipes will be arranged as near the upper part Jof the tank as conditions will permit.' lf arranged `in vretical stacks, they may form partitions within the bath adapted to receive piles of .the tanned skins.

llt will be understood ofcourse that the water should be Vof a nature that willnot affect the leather by the deposit of objectionable salts tending to impair or affect the leather. A. naturally soft kwater is preferred, n

land it is within the scope of my invention to treat the water so that it will be wholly innocuous so faras its effect upon the leather is concerned while maintaining such leather completely wet and at a low temperature.

It is well known, of course, that mineral (chrome) tanned leather has a bluishY tinge or cast which, of course, must be overcome by the coloring operation.v

I claim: f

1. In the manufacture of leather in which the leather has been chrome-tanned, the step which comprises transferring said tanned skins While in a wet condition from the last step of the tanning operation to a cold Water bath in which said skins are stored, and maintaining said cold water bath at a relatively definite low temperature while said skins are stored therein. V

2. In the manufacture of leather in which the leather has been chrome-tanned, the step which comprises transferring said tanned skins while wet from the last step of the tanning operation to a bath of cold water, storing said skins therein and maintaining saidrbath at a temperature between 35 vF. and 45 F. l

substantially constant temperature between 35 F. and 45 F., and thereafter colormg said leather.

Y 8. Inv the vmanufacture of chrome-tanned glazed leather, subjecting the completely tanned skins tostorage in a cold water bath subsequent to the tanning operation and prior to the coloring and finishing operations.

In witness whereof I have signed this specification. Y PETER A. BLATZ.

3. In the manufacture of leather in which i the leather has been chrome-tanned, the steps which comprise removingA the tanned skins from the last tanning bath in the completely saturated and wet condition and storing them in a bath of cold water, and maintainoperation in a bath of cold water maintained at a predetermined low temperature.

6. In the manufacture of leather in which the leather has been chrome-tanned, the steps which comprise transferring the wet tanned leather from the final tanning bath to a bath of cold water, storing said leather therein while maintaining said cold water bath at a substantially constant low temperature, and thereafter coloring said leather.

7. In the manufacture of leather in which the leather has been chrome-tanned, the steps which comprise transferring the wet tanned leather from the final tanning bath to a bath of cold water, storing said leather therein while maintaning said coldA water bath at a l 1ro 

